Palaeontologists have discovered a new fossil species called Cloudina carinata, a small fossil with a tubular appearance and one of the first animals that developed an external skeleton between 550 and 543 million years ago. The discovery is documented in Precambrian Research.

The fossils were found in the archaeological site El Membrillar (Badajoz), one of the few sites in Europe where the remains of Cloudina can be found. "The specimens display exceptional preservation, they appear preserved in three dimensions, and show their original form and numerous details of the shells", lead author Iván Cortijo says. "Cloudina carinata is characterized by its elaborate ornamentation and complexity of the shells and tube that are formed when inserted."

The discoverers say the fossils show evidence of asexual reproduction which was previously found only in Chinese specimens of Cloudina", and are some of the "oldestexamples of reproduction in animals in the fossil register."

Well-preserved fossils of Cloudina carinata were found in Extremadura.

(Photo Credit: Cortijo et al.)

The discovery of new species of Cloudina is important "for understanding the early evolution of animals," as well as "the origin of skeletons," says Cortijo. Despite the fact that its relation to other groups of animals is uncertain, Cloudina has been compared to cnidaria (medusas and corals) and annelida (polychaeta sea worms, earthworms and leeches).

Study of fossils from the Ediacaran period (between 630 and 540 million years ago) and of other fossils from the early Cambrian (540 million years ago) reveals the path followed by evolution at a crucial moment in the history of life, when the first animals appeared. This first evolutionary radiation of animals reached its apex in the so-called "great Cambrian explosion" or "Big-Bang of evolution".

In the '70s specimens of Cloudina were discovered for the first time in Namibia and later they were discovered in Oman, southern China and the south-east of the USA. According to scientists, it is a fossil indicative of the terminal Ediacaran, which marks the end of the Proterozoic eon, and gives way to the Phanerozoic, when the great radiation of animals began.

Citation: Cortijo et al., 'A new species of Cloudina from the terminal Ediacaran of Spain', Precambrian Research, January 2010, 176(1-4), January 2010, 1-10; doi:10.1016/j.precamres.2009.10.010